A short history of cathodic protection, from the discovery of its operating principle about 1800 and its use by Sir Humphry Davy a few years later, is followed by a description of where and how corrosion of metal occurs, the use of wrapping and of a sand bed around a pipeline, cathodic protection of pipelines,and of steel-piled jetties, appropriate levels of impressed current, and the prevention of sparking between a berthing ship and a cathodically protected petroleum jetty.
Periodic verification of the effectiveness of both impressed-current and sacrificial-anode systems of cathodic protection is necessary, and worn-out anodes have to be replaced. The Author describes the half-cells of copper/copper sulphate and silver/silver chloride which are used for testing protection systems in soil and sea water respectively, and states appropriate voltage levels for each. The Paper also describes a typical cathodic protection installation with impressed current.
